Identify the finding seen in this hysterosalpingogram:

Correct Answer: C. Bilateral hydrosalpinx

Hydrosalpinx is a fluid-filled, dilated fallopian tube resulting from distal tubal occlusion with proximal patent segment. On hysterosalpingogram (HSG), the classic finding is a dilated, tortuous tube with a blunt, closed distal end that fails to spill contrast into the peritoneal cavity. In bilateral hydrosalpinx, both tubes show this characteristic appearance—smooth, progressively dilated tubes resembling a "sausage" or "retort" shape, with contrast pooling within the lumen but no peritoneal spillage. The key discriminator is that the tubes remain patent proximally (contrast enters from the uterine cavity) but are occluded distally (no spillage). This differs from cornual block, where occlusion occurs at the uterotubal junction itself, preventing contrast entry into the tube. Hydrosalpinx is commonly seen in India following pelvic inflammatory disease (PID), tuberculosis (TB), or post-surgical adhesions. The dilated appearance with fluid accumulation is pathognomonic and represents a significant cause of infertility due to impaired oocyte transport and altered endometrial receptivity. The bilateral presentation suggests a systemic process, often TB salpingitis in the Indian context.

Why the other options are wrong

A. Bilateral cornual block — Cornual block (uterotubal junction obstruction) prevents contrast from entering the tube at all—the tube remains collapsed and non-visualized on HSG. In hydrosalpinx, contrast clearly enters and dilates the proximal tube before pooling distally. NBE may trap students who confuse 'tubal block' with any tubal pathology, but the location and appearance differ fundamentally. B. Extravasation into venous system — Venous intravasation occurs when contrast enters uterine veins (seen as linear opacification of pelvic veins), typically indicating uterine perforation or severe endometrial pathology. Hydrosalpinx shows contrast confined within the dilated tubal lumen with a smooth, closed distal end—no vascular uptake. This is a common NBE distractor for students unfamiliar with HSG interpretation patterns. D. Normal HSG — Normal HSG shows bilateral tubes that taper gradually toward the fimbriae and spill freely into the peritoneal cavity (free peritoneal spillage). Hydrosalpinx demonstrates dilated, non-tapering tubes with blunt distal ends and absent spillage. The dilated appearance is unmistakable and rules out normality entirely.

High-Yield Facts

Mnemonics

HYDRO = Dilated tube Huge dilated tube, Yet patent proximally, Distal occlusion, Retort/sausage shape, Obstructed spillage. Use this to recall the pathognomonic appearance on HSG. Cornual vs Hydro Cornual = tube not entered (no contrast in tube). Hydro = tube entered and dilated (contrast pools inside). Think: Cornual = blocked at gate; Hydro = gate open, room flooded.

NBE Trap

NBE pairs "tubal block" terminology with cornual block to trap students who don't distinguish between uterotubal junction occlusion (cornual) and distal tubal occlusion with proximal patency (hydrosalpinx). Both show "blocked" tubes, but HSG appearance and clinical implications differ entirely.

Clinical Pearl

In India, bilateral hydrosalpinx in a young woman with infertility should raise suspicion for genital tuberculosis (endemic in high-burden TB states); HSG findings must be correlated with TB serology, endometrial biopsy, and laparoscopy. Even unilateral hydrosalpinx warrants TB screening before pursuing fertility treatment.

_Reference: DC Dutta's Textbook of Gynaecology (6th ed.), Ch. 12 (Infertility); Harrison's Principles of Internal Medicine, Ch. 297 (Imaging in reproductive medicine)_